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Gene Doctors Milk Mice; Yield Human Breast Milk Protein

James Owen
for National Geographic News
June 2, 2009
 
An experimental farm in Russia could soon be producing human breast milk substitutes following successful milking trials on mice, scientists report.

Thanks to human genes spliced into their genome, the mice are the first genetically modified animals to produce lactoferrin. This human breast milk protein protects babies from viruses and bacteria while the infants' immune systems are still developing (get a quick genetics overview).

The ultimate aim of the Russian team, and of similar research projects in other countries, is to extract lactoferrin from the milk and use the protein to create healthier baby formula.

"Mouse milk is very protein-rich, and this can also translate into very high concentrations of transgenic protein," Patrick van Berkel, a senior director at the Danish biotech company Genmab, wrote in an email.

Breastfeeding mothers typically produce 4 to 5 grams (0.1 to 0.2 ounces) of lactoferrin per liter (about a quart) of milk.

The modified mice churned out maximum concentrations equal to 160 grams (6 ounces) per liter, said team member Elena Sadchikova of the Institute of Gene Biology at the Russian Academy of Sciences in Moscow.

But that doesn't mean the mice themselves are about to become biotech dairy animals, Sadchikova cautioned.

To milk mice, the research team had to anaesthetize the rodents and use specially adapted pumps fitted to their tiny teats.

If attempted commercially, "the scale at which this would have to happen would be a logistic and technical nightmare," van Berkel said. "Larger animals such as rabbits, goats, or cows are required for commercial application."

(Related: "Horse Taming, Milking Started in Kazakhstan.")

Rabbit-Milk Drugs

Rabbits bred with human genes are already being milked commercially by Netherlands-based biotech company Pharming.

The rabbit milk contains a human protein used in a new drug treatment for hereditary angioedema, a rare blood disorder that can lead to severe swelling of body tissues.

"When you make a medicine, the volumes [of protein] you need are relatively limited," noted Pharming CEO Sijmen de Vries.

"Whereas if you're going to make human lactoferrin, which eventually you want to use, say, in infant formula, then you need very significant volumes."

De Vries predicts that human lactoferrin from cow milk will be available for commercial use in two to three years.

The Russian team, however, favors transgenic goats, according to the Institute of Gene Biology's Sadchikova.

(Related: "Lab Spins Artificial Spider Silk, Paving the Way to New Materials.")

"The most attractive advantage of a goat is that its pregnancy period is twice [as short as] that of a cow," she said, which means a herd could be established fairly quickly.

"A goat also reaches breeding age three times faster than a cow … has good resistance to illnesses, and does not share any diseases with a human being."
 

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